1. Field of the Invention
This invention is generally directed to miniature fuses of the type which are normally associated with automotive vehicles and more specifically to blade type terminal fuses which are adapted to provide a tappable electrical connection for use in installing auxiliary electrical equipment within a vehicle or other equipment without requiring the electrical wiring or electrical harnesses associated with the electrical system of the vehicle or equipment to be disturbed or spliced. The tap fuses of the present invention permit auxiliary electrical equipment to be connected to a vehicle or other electrical system by directly tapping a source of electrical power through the fuse elements conventionally associated with such systems. In one embodiment of the invention, one of the blade terminals of each fuse extends outwardly or is spaced from the fuse housing so as to be accessible to a female electrical connector mounted at the remote or free end of an electrical wire or cable associated with the auxiliary equipment being installed.
In one form of the invention, the auxiliary blade terminal extends from the insulated housing which normally surrounds the terminals of the fuse so that the electrical connection is made exteriorly with respect to the housing. In this embodiment, the auxiliary terminal may be selectively covered by a protective insulated cap when not in use.
In another form of the present invention, the auxiliary blade terminal may be mounted within in a recess within the housing which recess is of a size to permit a female electrical connector to be inserted therein to electrical contact the auxiliary blade terminal.
In another embodiment of the present invention, both of the blade terminal elements of the fuse will include remote auxiliary end portions which may be tapped by a pair of electrical connectors mounted to the remote or free ends of a pair of wires or electrical conductors which extend to a remote fuse condition indicator panel. In this manner, the condition of the fuse element may be displayed to a remote location such as the dashboard of the vehicle so that the vehicle operator will have an immediate indication as to a blown fuse. In this embodiment, the auxiliary blade terminal elements may either be recessed within the housing or extend from the housing as in the case with the first embodiment of the invention.
2. Description of the Related Art
Until recently, the automotive and other industries have relied entirely on conventional cylindrical glass fuses to protect against electrical overloads and overheating in low amperage electrical wiring. Such fuses are generally placed in electrical circuits so as to prevent an overload due to faulty wiring or equipment conditions with the amperage ratings of the fuse elements generally not exceeding 25 amps. In vehicles, such electrical systems may control the operation of headlights, tail lights, running lights, dashboard lights, instrumentation, horns, wiper systems, electrical doors, windows and locks, radios and other associated equipment. As many vehicle operators have experienced over the years, the simple matter of a blown fuse in an electrical circuit can be a very complicated and time consuming replacement project.
Often times the fuse panels or boxes for automotive and other equipment are placed in inconvenient locations, either beneath the dashboards or within closed compartments. Due to the complexity and the problems associated with replacing conventional glass type cylindrical fuses, the automotive and other industries have begun utilizing what are known as miniature blade fuses. Blade fuses are more compact and easily handled during replacement and removal and provide not only an economy of space but are easier to manipulate when being placed into an electrical panel or box. Miniature blade fuses are generally constructed of a conductive metallic material which is embedded into an insulated housing which is easily gripped for manipulation. The fuses include parallel and coplanar terminal blades that extend outwardly so as to be engagable within the sockets provided within fuse boxes or panels. The terminals are connected by a thin strip of conductive material which extends between the terminals within the housing. The housings are generally designed so that when the thin fuse strip overheats and melts or breaks an indication of the failed condition of the fuse is easily discernable through the housing. Examples of such prior art blade type fuses are disclosed in U.S. Pat. Nos. 3,909,767 to Williamson et al and 4,999,447 to Greenberg.
Unfortunately, although there has been significant improvement in the economy and the handling of fuse elements utilized in flat blade type fuses, there remain problems which are encountered on a regular basis with respect to the installation of new electrical equipment into a vehicle's or other equipment's electrical system. In many instances, it may be desired to install auxiliary electrical equipment such as radios, cassette players, television sets and telephones into cars, trucks, vans and the like. When this equipment is installed in a vehicle, it must be connected to the vehicle electrical system. In order to accomplish this, prior art techniques have required that the electrical line from the equipment be tapped to one of the electrical wires leading to or from the fuse box or fuse panel. This type of connection not only is unsafe but requires a great deal of experience in knowing which lines of the electrical system can be appropriately spliced to provide power to the auxiliary electrical equipment. This process is both time consuming and costly and often requires the need of experienced personnel. However, even with experienced personnel, electrical harnesses are often overly complex and require that electrical diagrams of the electrical system be available. This requires that installers have access to the electrical diagrams of many types of automotive vehicles or other electrical systems.
Even with sufficient knowledge to install such auxiliary equipment, a great deal of work is often involved when it becomes necessary to disassemble a wiring harness and obtain a splice connection with an appropriate electrical line. To forego this problem, some installers make an electrical connection directly with one of the fuse elements or fuse contacts in a fuse box. This is generally accomplished by taking a small gauged electrical wire and wrapping it around the blade contact of a conventional blade type fuse and then inserting the fuse back into to its electrical socket. Such splices are not only unsafe but are not reliable. Due to the small dimensions between the terminal blades of conventional blade fuses, any attempt to wrap or otherwise attach a supplemental electrical wire to one of the blade terminals can result in an arcing between the terminals creating a safety problem or resulting in the destruction of the fuse element. Further, many auxiliary electrical lines include larger gauge electrical wire and are not therefore easily wrapped, soldered or secured to the terminal blades. In these instances, a secondary splice must be made between the large wire and a smaller wire and thereafter the mechanical splice being made to the blade terminal of the flat blade fuse.
Even without regard to the obvious safety problems involved with making mechanical splices to existing blade type fuses, due to the remote location of the fuse elements themselves, installation can be extremely difficult. Even where the splice is made while the fuse is out of a fuse box, attempting to re-align the fuse blades to their proper contacts within the box with the auxiliary electrical wire attached thereto can be a challenging task.
In view of the foregoing, it is necessary to provide a convenient, easy, safe and reliable method for providing a connection to a source of electrical energy for auxiliary electrical equipment especially in automotive vehicles. Further, by providing a source of tappable electrical energy through a fuse element, it is possible to install the equipment in a safe manner insuring that the electrical line will be protected from overload and overheat conditions.